This document describes a mechanism for a variable valve control of overhead-valve (OHV) internal combustion piston engines. An OHV engine is typically defined as an engine that has poppet type intake and/or exhaust valves located in the engine cylinder head, one or more camshafts located in the cylinder block, and with the valves being actuated via lifters, pushrods and rocker arms. OHV engines may be of various cylinder configurations such as vee, in-line or opposed. The OHV engine architecture is widely used because it is economical to manufacture, provides a compact physical package size and is reliable in service
Variable valve control is a very desirable feature in an engine because it can reduce exhaust emissions, reduce fuel consumption and improve power output characteristics. There are several known methods of variable valve control, such as electromagnetic (U.S. Pat. No. 4,777,915) or hydraulic (U.S. Pat. No. 6,739,293). However, these systems typically require complex and expensive control systems and tend to be unreliable in service. There are also mechanical systems (U.S. Pat. No. 6,792,903) but these typically require an overhead cam type engine architecture, which can be expensive to manufacture. Therefore, what is needed is a mechanical variable valve control device that can be incorporated into an OHV type engine.